a diagram, and write the differential
energy balance equation, eliminating any
terms that are zero or negligible. State
whether the system is open or closed.
Also state whether any heat or work is
positive or negative.
(a) Crude oil is pumped through a
cross-country pipeline. The pipe
inlet is 200 m higher than the outlet,
the pipe diameter is constant, and
the pump is located near the mid-
point of the pipeline. The entire
pipeline is insulated. System: pipe-
line and its contents.
(b) Nitrogen and hydrogen are fed at a
constant rate to a reactor operating
at steady state, where they react to
ammonia. The inlet and outlets have
the same diameter and the same
height above the ground. System:
reactor and its contents.
(c) Milk is pumped continuously
through the inner pipe of a double-
pipe heat exchanger, where it is
heated from 25°C to 80°C. System:
the inner pipe and its contents.